Air contamination during medical treatment results in deposits of microemboli in the lungs: An autopsy study

Parametric study of a bubble removing device for hemodialysis

BACKGROUND

This paper sets out to design a device for removing bubbles during the process of hemodialysis. The concept is to guide the bubbles while traveling through the device and eventually the bubbles can be collected. The design focuses on the analysis of various parameters i.e. inlet diameter, inlet velocity and size of the pitch. The initial diameters of Models 1 and 2 have thread regions of 6 and 10 mm, respectively.

PARAMETERS

Swirl number, Taylor number, Lift coefficient along with pressure field are also implemented.

RESULTS

Based on computational fluid dynamics analysis, the bubbles' average maximum equilibrium position for Model 1 reached 1.995 mm, being greater than that of Model 2, which attained 1.833 mm. Then, 16,000 bubbles were released into Model 1 to validate the performance of the model. This number of bubbles is typically found in the dialysis. Thus, it was found that 81.53% of bubbles passed through the radial region of 2.20 ± 0.30 mm. The appropriate collecting plane was at 100 mm, as measured from the inlet position along the axial axis. The Taylor number, Lift coefficient, and Swirl number proved to be significant parameters for describing the movement of the bubbles. Results were based on multiple inlet velocities. It is seen that Model 3, the improved model with unequal pitch, reached a maximum equilibrium position of 2.24 mm.

CONCLUSION

Overall, results demonstrated that Model 1 was the best design compared to Models 2 and 3. Model 1 was found capable of guiding the bubbles to the edge location and did not generate extra bubbles. Thus, the parametric study, herein, can be used as a prototype for removing bubbles during the process of hemodialysis.

Venous chambers in clinical use for hemodialysis have limited capacity to eliminate microbubbles from entering the return bloodline: An in vitro study

BACKGROUND

During hemodialysis (HD), blood passes through an extracorporeal circuit (ECC). To prevent air administration to the patient, a venous chamber (chamber) is located before the blood return. Microbubbles (MBs) may pass through the chamber and end up as microemboli in organs such as the brain and heart. This in vitro study investigated the efficacy of various chambers in MB removal.

MATERIALS AND METHODS

The in vitro recirculated setting of an ECC included an FX10 dialyzer, a dextran-albumin solution to mimic blood viscosity and chambers with different flow characteristics in clinical use (Baxter: AK98 and Artis, Fresenius: 5008 and 6008) and preclinical test (Embody: Emboless®). A Gampt BCC200 device measured the presence and size of MBs (20-500 μm). Percentage change of MBs was calculated: ΔMB% = 100*(outlet-inlet)/inlet for each size of MB. Blood pump speed (Qb) was 200 (Qb200) or 300 (Qb300) ml/minute. Wilcoxon paired test determined differences.

RESULTS

With Qb200 median ΔMB% reduction was: Emboless -58%, AK98 -24%, Fresenius 5008 -23%, Artis -8%, and Fresenius 6008 ± 0%. With Qb300 ΔMB% was: Emboless -36%, AK98 ± 0%, Fresenius 5008 ± 0%, Artis +25%, and Fresenius 6008 + 21%. The Emboless was superior to all other chambers with Qb200 and Qb300 (p < 0.001). Further, the Emboless with Qb300 still eliminated more MBs than all other chambers with Qb200 (p ≤ 0.003).

CONCLUSION

The results from the present study indicate that flow characteristics of the chamber and the Qb are important factors to limiting exposure of MB to the return bloodline. The Emboless chamber reduced MBs more effective than those chambers in clinical use investigated.

Novel Capped-Needle Device: A Novel Safety Feature to Eliminate Air Bubbles in Hemodialysis

INTRODUCTION

Air bubbles in the dialysis circuit are rarely visible after automatic priming; however, they are often visible after the needles are manually connected to the circuit. To prevent this issue, we thought to prime needles with a circuit at automatic priming by the hemodialysis machine. In order to achieve this idea, we designed and manufactured a novel capped needle to connect the needles to the extracorporeal circuit before the automatic priming of the hemodialysis machine. This study investigated the effectiveness of this novel capped needle and compared it with the conventional method for preventing air bubble contamination.

METHODS

We tested novel capped needles ten times to evaluate whether the dialysis machine works appropriately and removes air bubbles even with the attached capped needle. Next, we performed 25 trials using the conventional method, in which skilled nurses manually connect the needle. In both methods, we thoroughly counted the air bubbles with our naked eyes. We predicted that the capped needle would leave few bubbles in the circuit. In order to evaluate fewer bubbles, we conducted an additional experiment using a microparticle counter to measure the size and number of the bubbles.

RESULTS

We thoroughly searched for air bubbles during each of the ten tests but could not find any bubbles visible to the naked eye. In the conventional method, bubbles were visible in 29 out of 50 cases. The bubble count was significantly lower in the capped-needle method than in the conventional method (p < 0.0001, Pearson's χ2 test). In the additional experiments using the microparticle counter, the average remaining air volume in the extracorporeal circuit was 0.0999 ± 0.2438 nL when the priming was performed using the novel capped needles.

CONCLUSION

The novel capped needle eliminated all visible bubbles efficiently and effectively; therefore, it could be a valuable device for hemodialysis treatment. The reduction of air from the dialysis circuit may improve patient prognosis.

Microemboli induced by air bubbles may be deposited in organs as a consequence of contamination during medical care

Background

Larger volumes of accidental air infused during medical care may end up as emboli while microbubbles of air are supposed to be absorbed and cause no harm. The aim of this autopsy study was to investigate if microbubbles of air accidently entering the bloodline may be detected as microemboli (ME) in tissue such as lungs, brain and heart. If so, do differences in prevalence exist between haemodialysis (HD) and amyotrophic lateral sclerosis (ALS) patients.

Methods

Included were data from 44 patients treated by medical healthcare before death. Twenty-five cases had been treated with chronic HD and 19 cases died from ALS. Since air in the bloodline activates coagulation, ME could appear. To discriminate between microbubbles caused by artificial contamination during autopsy versus microbubbles deposited in vivo, tissues were stained with a polyclonal fluorescent antibody against fibrinogen, fibrin and fragments E and D. Fluorescence staining was used to visualize ME counted within 25 microscopic fields (600×) of a tissue preparation. One tissue preparation was used if available from the lung, heart and frontal lobe of the brain and in five cases also the cerebellum.

Results

Microbubbles can be verified at autopsy as ME in the lung, heart and brain in tissue from patients exposed to more extensive medical care. There were significantly more ME in the lungs versus the heart or brain. Women had fewer ME than men. The HD group had a higher median of ME per section than the ALS group (lung: 6 versus 3, P = .007; heart: 2.5 versus 1, P = .013; brain: 7.5 versus 2, P = .001) and had more sections with ME findings than the ALS group (P = .002). A correlation existed between the time on HD (months) and ME in the lungs.

Conclusions

More ME were present in HD patients compared with those who suffered from ALS. Minimizing air contamination from syringes, infusions and bloodlines will decrease ME and subsequent tissue injury.

Wearable and implantable artificial kidney devices for end-stage kidney disease treatment-Current status and review

BACKGROUND

Chronic kidney disease (CKD) is a major cause of early death worldwide. By 2030, 14.5 million people will have end-stage kidney disease (ESKD, or CKD stage 5), yet only 5.4 million will receive kidney replacement therapy (KRT) due to economic, social, and political factors. Even for those who are offered KRT by various means of dialysis, the life expectancy remains far too low.

OBSERVATION

Researchers from different fields of artificial organs collaborate to overcome the challenges of creating products such as Wearable and/or Implantable Artificial Kidneys capable of providing long-term effective physiologic kidney functions such as removal of uremic toxins, electrolyte homeostasis, and fluid regulation. A focus should be to develop easily accessible, safe, and inexpensive KRT options that enable a good quality of life and will also be available for patients in less-developed regions of the world.

CONCLUSIONS

Hence, it is required to discuss some of the limits and burdens of transplantation and different techniques of dialysis, including those performed at home. Furthermore, hurdles must be considered and overcome to develop wearable and implantable artificial kidney devices that can help to improve the quality of life and life expectancy of patients with CKD.

Interdialytic weight gain of less than 2.5% seems to limit cardiac damage during hemodialysis

Aims:

To investigate if a single low-flux HD induces a rise in cardiac biomarkers and if a change in clinical approach may limit such mechanism.

Material and methods:

A total of 20 chronic HD patients each underwent three different study-dialyses. Dialyzers (low-flux polysulfone, 1.8 sqm) had been stored either dry or wet (Wet) and the blood level in the venous chamber kept low or high. Laboratory results were measured at baseline, 30 and 180 min, adjusted for the effect of fluid shift. Ultrasound measured microemboli signals (MES) within the return line.

Results:

Hemodialysis raised cardiac biomarkers (p < 0.001): Pentraxin 3 (PTX) at 30 min (by 22%) and at 180 min PTX (53%), Pro-BNP (15%), and TnT (5%), similarly for all three HD modes. Baseline values of Pro-BNP correlated with TnT (rho = 0.38, p = 0.004) and PTX (rho = 0.52, p < 0.001). The changes from pre- to 180 min of HD (delta-) were related to baseline values (Pro-BNP: rho = 0.91, p < 0.001; TnT: rho = 0.41, p = 0.001; PTX: rho = 0.29, p = 0.027). Delta Pro-BNP (rho = 0.67, p < 0.001) and TnT (rho = 0.38, p = 0.004) correlated with inter-dialytic-weight-gain (IDWG). Biomarkers behaved similarly between the HD modes. The least negative impact was with an IDWG ⩽ 2.5%. Multiple regression analyses of the Wet-High mode does not exclude a relation between increased exposure of MES and factors such as release of Pro-BNP.

Conclusion:

Hemodialysis, independent of type of dialyzer storage, was associated with raised cardiac biomarkers, more profoundly in patients with higher pre-dialysis values and IDWG. A limitation in IDWG to <2.5% and prolonged ultrafiltration time may limit cardiac strain during HD, especially in patients with cardiovascular risk.